Zhang Xiaoming raised HK$11m by singing a song at the DAB's fund-raising dinner.

Any idea which of the city's political parties is the wealthiest?

If the biggest - the pro-Beijing Democratic Alliance for the Betterment and Progress of Hong Kong (DAB) - claims it's No 2 on the rich list then it's hard to imagine another political grouping would be game to say it was more flush with cash.

The party raked in a record HK$63.8 million at its recent fund-raising dinner. Central government liaison office director Zhang Xiaoming certainly did his bit. His own work of calligraphy was auctioned off at the dinner for HK$13.8 million. Zhang then took to the stage, singing a song to raise more cash for the party - to the tune of HK$11 million.

Founded in 1992, the DAB holds 13 seats in the Legislative Council - more than any other party. And 133 of its members are district councillors. As the party seen as the most supportive of Beijing and the Hong Kong government, it is no surprise when a senior figure such as Zhang throws his weight behind the party - financially and otherwise.

But while the record amount raised was the talk of the town last week, the dinner also put another issue in the spotlight: should political parties open their finances to public scrutiny?

Legislation forcing parties to do just this has long been mooted. But the dinner also had the city speculating about whether the DAB's political and financial clout would inevitably mean it would one day become the city's "ruling party".

Certainly its chairman, Tam Yiu-chung, is doing little to hide his ambitions on this front. He recently revealed he had been encouraged by "many friends" who considered the DAB the party in the best position to lead the city - and therefore it should be able to field a candidate for the 2017 chief executive poll.

But Tam did concede there would be "many difficulties ahead" in achieving this goal.

That's an understatement. Becoming a ruling party in Hong Kong would require more than just setting a goal and working towards it. Beijing's blessing would of course be required, along with public support, while other practicalities would need to be tackled.

Aside from the fact that the Basic Law does not allow the city's leader to have any party affiliation - meaning the DAB's hopes of becoming a ruling party are unlikely as any candidate it supported for the top job would not be able to represent the party - there is another problem: finances.

Political parties in Hong Kong are either registered as a company or a society as there is no legislation requiring such organisations to make their donations and finances public.

It's not just the DAB, of course. With no reason to divulge the details of their finances, it's only fund-raising events that give the media - and the public - any clue as to where parties' funding comes from.

So the DAB may well argue that it is unclear whether it is the wealthiest party because of this lack of transparency.

There is also the issue of anonymous donors, and parties that may have money coming in from overseas. While some high-fliers in town don't mind making it known that they donate to a pro-Beijing party such as the DAB, others prefer to do so anonymously - especially when their money is going to the pan-democratic camp.

Money aside, the parties are also grappling with the reality of the situation: the chance for them to become the ruling party is slim, if not impossible, at least for the foreseeable future. Not just because of the restriction on the chief executive, but also due to the fact that no party holds a clear majority among Legco's 70 seats.